if(array_height_2d(self.tiles) != 0)
{
    for(var iii = 0; iii < array_height_2d(self.tiles); iii++)
    {
        for(var jjj = 0; jjj < array_length_2d(self.tiles, iii); jjj++)
        {
            if(tiles[iii, jjj] != 0)
            {
                with(self.tiles[iii, jjj]) 
                {
                    instance_destroy();
                }
            }
        }
    }
}